1. Field of the Invention
The present invention relates to a radiation-sensitive colored composition which is preferable for the production of a color filter used for a liquid crystal display apparatus, a solid state image device, or the like; a color filter and a method for producing the same; and a solid state image device and a liquid crystal display apparatus, each of which includes the color filter.
2. Description of the Related Art
As one of the methods for producing a color filter used for a liquid crystal display apparatus, a solid state image device, or the like, a pigment dispersion method may be exemplified. This pigment dispersion method is a method in which a color filter is produced by a photolithographic method from a radiation-sensitive colored composition formed by dispersing a pigment in any one of various curable compositions. Specifically, the radiation-sensitive colored composition is coated on a substrate by using a spin coater, a roll coater, or the like, then dried to form a coating film, and thereafter, the coating film is pattern-exposed and developed to obtain colored pixels. This procedure is repeated by the number of desired colors to prepare a color filter.
With this method, the color filter is stable with respect to light or heat due to the use of the pigment and a positional accuracy is sufficiently secured by performing patterning by a photolithographic method. Therefore, this method has widely been used as a method which is preferable for producing a color filter for a color display, or the like.
On the other hand, the color filter for the solid state image device such as a CCD and the like has been required to be preciser in recent years. Although the color filters tend to have a smaller pattern size with higher precision, it is thought that it is difficult to provide a smaller pattern size and further improved resolution in the pigment dispersion method that has been conventionally used. One of the reasons for this is that coarse particles generated by aggregation of the pigment particles are one of the causes of occurrence of color unevenness in the fine pattern.
Therefore, for example, suppressing or preventing the display failure of a liquid crystal display by reducing the content of free copper contained in the pigment among the ionic impurities contained in the pigment in order to provide a color filter having excellent display performance has been investigated (see, for example, JP2001-166124A).
However, in recent years, there has been a situation in which the pigment dispersion method that has been hitherto used for general purposes is not necessarily suitable for applications requiring fine patterns, for examples, for a solid state image device.
Under these circumstances, using a dye as a colorant in order to accomplish high precision has been conventionally investigated (see, for example, JP1994-75375A). However, a dye in the molecular dispersion state has a problem that it is inferior to a pigment in terms of the preservation stability of a resist liquid, light resistance, heat resistance, solvent resistance, or the like. With respect to such a problem, improving the preservation stability of a resist liquid or light resistance has been investigated (see, for example, JP2007-94188A).
As an alternative method, a method for polymerization of a dye has been proposed (see, for example, JP2007-138051A, JP2007-139906A, and JP3736221B). However, it is hard to say that this method can fully solve the problems regarding solvent resistance, color transfer, developability, and the like, and in addition, there are some cases where polymerization of a dye causes deterioration of the color unevenness, which thus needs to be further improved.